We have shown the feasibility of neoplastic induction in organ cultured embryonic pancreas grown in the presence of Dimethylnitrosamine (DMN). It is the purpose of this Project: To study the nature of neoplastic changes developed in pancreas explants. The explants will be examined by light and electron microscopes at various intervals after DMN treatment. It is also the aim of this study to identify and characterize the progenitor cells for neoplasia in this system by morphological, ultrastructural and biochemical parameters. BIBLIOGRAPHIC REFERENCES: Parsa, I. and Marsh, W.H. Longterm organ culture of rat pancreas rudiment in a synthetic medium: Morphological and enzymatic development. Am. J. Path. Jan., 1976. Parsa, I. Pancreatic neoplasia induced by dimethylnitrosamine in culture. Federation 1976 Abstract.